# Improve Codebase Architecture > Scan a codebase for deepening opportunities, present them as a visual HTML report, then grill through whichever one you pick. - Skill: `amornsit/improve-codebase-architecture` (Agent Skill, multi-file: 3 files) - Install (CLI): `npx skillmds@latest add amornsit/improve-codebase-architecture` - Raw SKILL.md: https://api.skillmd.com/api/skills/amornsit/improve-codebase-architecture/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Web & Frontend - Author: amornsit (https://skillmd.com/u/amornsit) - Updated: 2026-09-22 - Page: https://skillmd.com/skills/amornsit/improve-codebase-architecture --- # Improve Codebase Architecture Surface architectural friction and propose **deepening opportunities** — refactors that turn shallow modules into deep ones. The aim is testability and AI-navigability. This command is _informed_ by the project's domain model and built on a shared design vocabulary: - Read [codebase-design](../codebase-design/SKILL.md) for the architecture vocabulary (**module**, **interface**, **depth**, **seam**, **adapter**, **leverage**, **locality**) and its principles (the deletion test, "the interface is the test surface", "one adapter = hypothetical seam, two = real"). Use these terms exactly in every suggestion — don't drift into "component," "service," "API," or "boundary." - The domain language in `CONTEXT.md` gives names to good seams; ADRs in `docs/adr/` record decisions this command should not re-litigate. ## Process ### 1. Explore **Scope before you scan — YAGNI.** Deepening a module pays off by making future changes to it easier, so put extra weight on the parts of the codebase that have recently changed. Decide _where_ to look before you look: - If the user named a direction — a module, a subsystem, a pain point — take it, and skip the inference below. - Otherwise, walk back a good stretch of the commit history (`git log --oneline`) to find the codebase's hot spots — the files and areas that keep coming up — and let those paths pull your attention first. If the changes are scattered with no clear hot spot, widen the net. Read the project's domain glossary (`CONTEXT.md`) and any ADRs in the area you're touching first. Then use the Agent tool with `subagent_type=Explore` to walk the codebase. Don't follow rigid heuristics — explore organically and note where you experience friction: - Where does understanding one concept require bouncing between many small modules? - Where are modules **shallow** — interface nearly as complex as the implementation? - Where have pure functions been extracted just for testability, but the real bugs hide in how they're called (no **locality**)? - Where do tightly-coupled modules leak across their seams? - Which parts of the codebase are untested, or hard to test through their current interface? Apply the **deletion test** to anything you suspect is shallow: would deleting it concentrate complexity, or just move it? A "yes, concentrates" is the signal you want. ### 2. Present candidates as an HTML report Write a self-contained HTML file to the OS temp directory so nothing lands in the repo. Resolve the temp dir from `$TMPDIR`, falling back to `/tmp` (or `%TEMP%` on Windows), and write to `/architecture-review-.html` so each run gets a fresh file. Open it for the user — `xdg-open ` on Linux, `open ` on macOS, `start ` on Windows — and tell them the absolute path. The report uses **Tailwind via CDN** for layout and styling, and **Mermaid via CDN** for diagrams where a graph/flow/sequence reliably communicates the structure. Mix Mermaid with hand-crafted CSS/SVG visuals — use Mermaid when relationships are graph-shaped (call graphs, dependencies, sequences), and hand-built divs/SVG when you want something more editorial (mass diagrams, cross-sections, collapse animations). Each candidate gets a **before/after visualisation**. Be visual. For each candidate, render a card with: - **Files** — which files/modules are involved - **Problem** — why the current architecture is causing friction - **Solution** — plain English description of what would change - **Benefits** — explained in terms of locality and leverage, and how tests would improve - **Before / After diagram** — side-by-side, custom-drawn, illustrating the shallowness and the deepening - **Recommendation strength** — one of `Strong`, `Worth exploring`, `Speculative`, rendered as a badge End the report with a **Top recommendation** section: which candidate you'd tackle first and why. **Use CONTEXT.md vocabulary for the domain, and `codebase-design`'s vocabulary for the architecture.** If `CONTEXT.md` defines "Order," talk about "the Order intake module" — not "the FooBarHandler," and not "the Order service." **ADR conflicts**: if a candidate contradicts an existing ADR, only surface it when the friction is real enough to warrant revisiting the ADR. Mark it clearly in the card (e.g. a warning callout: _"contradicts ADR-0007 — but worth reopening because…"_). Don't list every theoretical refactor an ADR forbids. See [references/html-report.md](references/html-report.md) for the full HTML scaffold, diagram patterns, and styling guidance. Do NOT propose interfaces yet. After the file is written, ask the user: "Which of these would you like to explore?" ### 3. Grilling loop Once the user picks a candidate, run [grilling](../grilling/SKILL.md) to walk the decision tree with them — constraints, dependencies, the shape of the deepened module, what sits behind the seam, what tests survive. Side effects happen inline as decisions crystallize — run [domain-modeling](../domain-modeling/SKILL.md) to keep the domain model current as you go: - **Naming a deepened module after a concept not in `CONTEXT.md`?** Add the term to `CONTEXT.md`. Create the file lazily if it doesn't exist. - **Sharpening a fuzzy term during the conversation?** Update `CONTEXT.md` right there. - **User rejects the candidate with a load-bearing reason?** Offer an ADR, framed as: _"Want me to record this as an ADR so future architecture reviews don't re-suggest it?"_ Only offer when the reason would actually be needed by a future explorer to avoid re-suggesting the same thing — skip ephemeral reasons ("not worth it right now") and self-evident ones. - **Want to explore alternative interfaces for the deepened module?** Read `codebase-design` and use its design-it-twice parallel sub-agent pattern. --- _Adapted from Matt Pocock's "improve-codebase-architecture" skill (github.com/mattpocock/skills) — MIT © Matt Pocock. `HTML-REPORT.md` moved to `references/html-report.md` with the context pointer repointed, and the `/codebase-design`, `/grilling`, and `/domain-modeling` slash commands turned into cross-skill links. See [NOTICE.md](../../NOTICE.md)._